Reversible bit and holder therefor



NOV. 13, 195] J, STEPHENS 2,575,239

REVERSIBLE BIT AND HOLDER THEREFOR Filed June 15, 1950 IN VEN TOR:

fobe ri fie hens Patented Nov. 13,

REVERSIBLE BIT AND HOLDER THEREFOR ,Robert J. Stephens, Montgomery, W. Va., assignor to Marathon Coal Bit Company, Inc., Mont-' gomcry, W. Va., a corporation of West Virginia Application June 13,1950,1Serial No. 167,729

. 1 This invention relates to certain new and useful improvements in reversible bits and holders therefor and has for its principalobject the provision of an improved construction-of this character which will e highly efficient in use and economical in manufacture.

An object of my inventionis to provide a reversible bit and holder therefor of the character hereinafter more fully set forth, especially useful for drilling any hard formation including all formations of earth strata or any synthetic product. The bit and holder therefor are especially designed for use by the coal mining industry for drilling blast holes, steel pin timbering holes, hanger holes, and the like.

A further and equally important object of the invention is to provide a reversible bit having opposed cutting heads with two reaming sides common to both heads whereby the cutting heads and the reaming sides may be sharpened whenever found desirable and necessary.

Another object of the invention is to provide a bit holder in which there is an arrangement for permitting the passage therethrough of air or water to facilitate and expeditethe drilling operation and to expel from the drilled hole the dust or like matter, brought about through the drilling operation.

Another object of the invention is to provide an attachment between the bit and the holder therefor whereby as the cutting head is reduced in size by reason of having been sharpened, the bit may be adjusted outwardly in a longitudinal direction from the holder.

Other objects will appear hereinafter.

The invention consists in the novel combination and arrangement of parts to be hereinafter described and claimed.

The invention will be best understood by reference to the accompanying drawings showing the preferred form of construction, and in which:

Fig. 1 is a side elevational view showing the bit holder and bit embodying my invention;

Fig. 2 is an edge view of the same;

Fig. 3 is a perspective view of the bit embodying my invention;

Fig. 4 is an end view of the same;

Fig. 5 is a sectional detail view taken substan-v tially on line 55 of Fig. 2; and

Fig. 6 is a sectional detail view taken substantially on line 6-6 of Fig. 2.

As hereinbefore stated, my improved bit and holder therefor is especially designed for use in the coal mining industry; however, the same may be used for drilling purposes other than in such industry.

1 Claim. "(01. 255-61) (not shown).

To accomplish the several objects of my iii-- vention, I provide a holder H formed as an integral part of a shank l0. This shank Ill is adapted to be mounted in a suitable driving chuck The head provides a transversely extending slot |,'the base of which is triangular. in plan view as at l2, with the apex [3 thereof intersecting a longitudinal passage l4 formed in the shank l0, and having communicating there- The bit embodying my invention is indicated at 9, and this bit provides oppositely disposed cutting heads 2|! and 2| and reamer side edges 22 common to both heads. The cutting heads are triangular in plan view to conform to the shape of the triangular section of the slot ll. These heads 26 and 2| provide cutting edges 23.

Formed in the bit l9 in parallel relation with respect to the reaming side edges 22 is an elongated slot 24 through which projects the threaded shank of the clamping bolt I.

In use, the bit is positioned in the slot ll between the fingers "5, with one of the cutting heads such as 2| (Fig. 5) positioned in the triangular shaped base of the slot II, the walls of which base cooperate with the adjacent edges of the head 2| to prevent movement of the cutting bit about the clamping screw l8. After the bit has been positioned in the slot H in the manner shown in Fig. 5, the clamping screw is adjusted to bear the fingers l6 into clamping engagement upon the adjacent side walls of the bit, thereby to rigidly clamp the bit within the slot The elongated slot 24 permits the bit l9 to be moved outwardly whenever its projecting cutting head is reduced in size by sharpening operation. As the cutting heads 20 and 2| are of similar construction, it is clearly manifest that the bit may be reversed to interchange the heads in cutting position.

The reaming side edges 22 result in the production of a hole which is'substantially uniform in diameter and eliminate what is known in the art as rifling action.

By providing the passage l4 and the branch passages l5, water may be forced into the hole during the drilling operation, thereby greatly facilitating such operation. On the other hand, air may be forced through these passages to remove the accumulated dust from the hole.

From the foregoing description, it will be of its adjustability, having substantially great longevity as compared with bits which are now in commercial use.

1 While Lhave illustrated and described, the pre:

ferred form of? construction for carrying my' invention into efiect, this is capable of variation 4 of which cutting heads being lnsertable in the said slot and each being triangular in plan view to conform to the shape of the base of said slot, and means for detachably connecting the bit in an adjusted position within said slot with one of the heads thereof projecting into the base of saidasldt saiddconnecting means, comprising a clamping screw threadediinto said. holder and projecting through an elongated slot formed in a d fic Without departing from the 10 the bit, said slot eirtending in a direction longispirit of the invention. 1, therefore, do not wish to be limited to the precise detailsliof"construction;

set forth, but desire to avail myself of such,variations and modifications as comewithinlthescope of the appended claim.

Having thus described my invention, what I claim as new and desire to protect; by Letters-= Patent is:

A tool of the class described comprising a shank, a holder integral -withthe shank at one end; thereof, and providing opposite its integral connection with ,theshanKa-transversely extend ing slot" opening atthe opposite side edge portions ofthe holder and at the end thereof; in a' longitudinal direction with: respect tothe; longaxis of." the shank, thetbaseoof-said slot being substantially triangular in cross section throughout the entire width of theholder, a bit having oppositely disposed aligned cutting heads: either tudinally with respect to the long axis of the shame-whereby:saidibit may be adjusted longitudinally, with respectto said shank.

' ROBERT J. STEPHENS.

law

REFERENCES CITED Tlie following references are of record in the 'filfinfiiithis patent:

UNITED STATES PATENTS 

